Question

当导师向挑战提出这个解决方案时，我正在观看Lynda.com PHP设计模式教程：

的index.php：

include_once 'decorator.php';

$object = new Decorator();
$object->sentence = "This is a sample sentence that we're going to manipulate in the Decorator.";

// This should output: this is a sample sentence that we're going to manipulate in the decorator.
echo $object->lower();

// This should output: THIS IS A SAMPLE SENTENCE THAT WE'RE GOING TO MANIPULATE IN THE DECORATOR.
echo $object->uppercase();

decorator.php：

class Decorator
{
    public $sentence = '';

    public function lower()
    {
        return strtolower($this->sentence);
    }

    public function uppercase()
    {
        return strtoupper($this->sentence);
    }
}

为什么这是一个装饰模式？我只看到对象的实例化并访问两个对象方法。

Answer 1

您发布的示例不是装饰器，它只是在字符串顶部提供新界面（lower和uppercase）。装饰器在不改变底层接口的情况下添加行为。

装饰器的典型示例是字面上装饰图形元素。例如：

interface Shape {
  draw();
}

class Rectangle implements Shape { ... }
class Circle implements Shape { ... }

class BorderDecorator implements Shape {
  Shape shape;

  draw() {
    shape.draw();
    drawBorder();
  }
}

上面的所有类都有相同的接口，所以如果一个函数需要Shape，你可以传入一个普通的Rectangle或者你可以将它包装在BorderDecorator中得到一个带边框的矩形。

Answer 2

你所做的不是装饰者模式。如果您真的想将实用程序类转换为decorator，那么您刚刚为字符串创建了Utility类，然后只看到下面的内容：

<?php

interface StringInterface
{
    public function string();
}

class StringDecorator implements StringInterface
{
    private $text;

    public function __construct($text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return  $this->text ;
    }
}


class StringLower implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return strtolower( $this->text );
    }
}
class StringUpper implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return strtoupper( $this->text );
    }
}
class StringTrim implements StringInterface
{
    private $text;
    public function __construct(StringInterface $text)
    {
        $this->text = $text;
    }
    public function string()
    {
        return trim( $this->text );
    }
}

// For Lowercase
$decorator=new StringLower( new StringDecorator("Text") );
// Output: Lowercase Text to text
$text=$decorator->string();

// For Uppercase
$decorator= new StringUpper( new StringDecorator("text") );
// Output: Uppercase text to Text
$text=$decorator->string();

//TO normalized text from " TeXT " to text.
$decorator= new StringTrim( new StringLower( new StringDecorator(" TeXT ") ) );
// Output: normalized text from " TeXT " to text also extra space removed from left and right.
$text=$decorator->string();

这是您的案例示例如果您需要更多真实世界的示例，请参阅here，我在这里给出了来自现实世界的好例子。

这是一个装饰模式（PHP）？

2 个答案: